I have a 98 a4 2.8 quattro. last week it started running hot, at 105 - 110 on the guage instead of 90. today i checked under the hood and noticed the upper rad hose is hot, but the lower hose is cold at operating temp. I am thinking it is a stuck closed thermostat but not sure. never owned an audi b4 and only had this one for 2 months. any ideas? a friend suggested the water pump but if it was toast the car would overheat right away and bury the guage right?

 

idk, but on my honda i had that problem and the fans got disconnected, forget the techincal name for that connection. Hooked them back up and it was fine. Dont know if it is the same problem.

 

was just out looking at it and the engine fan(clutch fan?) was turning so slow i stopped it and spun it the other way, with the engine running! seems unrelated to the overheating problem but the fan should be turning faster than 20rpm with the engine running!

 

If you rad hoses are not the same Temp @ operating Temp
then you most prob have a Stuck T/Stat
dats the first thing you have to fix
the Fans come in after you get good circulation

 

Change the termostat. Relatively cheap & I think that will solve your problem. just make sure that there are no blockages. If you are feeling mechanical you could flush your radiator.. . . Friend of mine, has a radiator so filled up with stop leak that it nearly blew the motor. Might be the same (bout I doubt it).

 

i have a 00 audi a4 1.9tdi, it started overheating to 100 degrees so i thought it must be the thermostat, so i took it out and drove it without a thermostat for awhile it ran at 70 degrees and never went above,so i went and bought a new thermostat put it in today and guess what??!!back to 100 degrees!! does anyone have any ideas on this??

 

Could simply be an air bubble at the thermostat that is not allowing it to open properly. If you burped it properly and there is no air I would then assume it is your water pump. Not enough force from the water pump to flow through the thermostat and open it. When was the waterpump last replaced?